Certain undesired mixtures of oil and water form distinct emulsions that are very difficult to break into separate oil and water fractions for recovery. One such emulsion category is the petroleum oil and water emulsions derived from producing or processing crude oil of our parent U.S. Pat. No. 4,971,703. One emulsion derived from the production of crude oil results from oil spills in the ocean.
Oil is in constant transit around the globe in a variety of forms. There have always been oil spill problems at sea, and this problem will most likely continue. Smaller magnitude oil spills also occur in harbors, rivers, lakes and streams. Two thirds of all oil spills occur during routine operations as a result of human error.
Recovery of oil spills concerns both the containment and collection of the spill, as well as recovery or disposal of that which is collected. Oil pollution of waterways from the production or processing of crude oil is a complex problem that must take into account the interaction of the oil, water and wind. It has been documented that several forms of oil and water emulsions occur and complicate the cleanup of oil spills. In the ocean, the presence of salt and other contaminants such as sand alter the physical properties of oil and water, making them difficult or impossible to treat with conventional technologies. Furthermore, much of the recovered spilled oil is of marginal or no use because it is too foamed and emulsified to effect adequate separation.
It is acknowledged that a crude oil-water emulsion changes in the aftermath of a spill. In the days immediately following a spill, the lighter fractions tend to vaporize. This results in thickening, leaving emulsions of the heavier fractions and water which are extremely difficult to collect or treat.
Crude oil is the primary source for liquid fuels. However, much research has been conducted in recent years for the development of processes for the production of liquid fuels from other sources. Such processes include, by way of example, the production of synthetic liquid fuel from coal and organic wastes by liquefaction. The separation of the formed liquid fuel from solid byproducts can be difficult in part because of solid and liquid contaminants. In our own development of a sludge-to-oil reactor system for producing fuel, liquid fuel is produced by thermal treatment of sewage sludge in the presence of added alkali. Such process is described in Research in Thermochemical Biomass Conversion, Elsevier Applied Science, pp. 867-881, a copy of which was provided with the Information Disclosure Statement accompanying the application from which this patent matured. Separation of the liquid fuel from residual water and inorganic components is expected to cause some difficulty using conventional technology.
The problems of dealing with oil and water emulsions is not confined to the petroleum processing industry or to oil contaminated spills. Discharge streams from food processing and other facilities can also contain fatty oil and water emulsions that must be treated.